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A rare inherited disease, called trimethylaminuria, means that the sufferer’s body fluids and breath smell of fish. This is because they cannot break down trimethylamine, which is naturally found in food, and it build up in their bodies.

Researchers have found magnetic particles in the olfactory epithelium (the cells involved in smell) of trout. These contain magnetite, and this is the first time that these have been found in animals with backbones (vertebrates). It’s not clear yet whether the fish use these to detect magnetic fields. Read the paper in PNAS.

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Before language, our sense of smell was very important to communicate relationships and identify mates, among other things, and we still have these abilities, though we don’t rely on them as much. Scientists collected body odour from volunteers using absorbent pads, and another team of volunteers was able to identify people’s ages from smell alone – and also found that older people smelled better than younger people.

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Having no sense of smell is called anosmia. Anosmia can be caused by a blow to the head, by a vitamin A deficiency, or by a viral infection. Famous anosmics include William Wordsworth (poet), Bill Pullman (actor), Brian Mulroney (Canadian Prime Minister), Michael Hutchence (lead singer of INXS) and Ben Cohen (Ben & Jerry’s Ice Cream).